estuary (khawr) separating Kuwait and Iraq, probably a drowned river mouth of the Shatt (stream) al-Arab, whose mouth is now farther north and forms the southeastern part of the border between Iraq and Iran. It extends into Iraqi territory in the form of the Khawr az-Zubayr, on which the Iraqi port of Umm Qaṣr is located and which is linked by canal northwestward to the Tigris–Euphrates River System. The Khawr ʿAbd Allāh borders the northeastern coast of the Jazīrat (island) Būbiyān and the northern coast of Jazīrat Warbah. Both islands are generally considered to be part of Kuwait but are also claimed by Iraq.